Retinoblastoma: Symptoms, Causes & Treatment

Retinoblastoma is a cancer that begins in the back of the eye. It can metastasize and affect surrounding tissues, making the treatment of this form of cancer difficult. 

This rare form of malignant cancer most commonly affects young children.

What Is Retinoblastoma?

Retinoblastoma is a malignant tumor that affects the cells of the retina, or the light-sensitive layer of tissue at the back of the eye that transmits visual information to the brain. 

Retinoblastoma is the most common form of eye cancer in young children. This type of cancer most commonly develops before the age of 5. If retinoblastoma is detected early, it can be successfully treated.

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Signs & Symptoms

Children may not be able to detect an abnormality in their vision themselves, so look for the following signs:

• Swelling of the eyes
• Redness 
• Complaints from the child about not being able to see very well or having blurred vision
• Eyes that are not fixed and may be looking in different directions from one another
• A white pigmentation in the pupil when light enters the eye, which may be noticeable in photographs
• Complaints of pain in the eye
• Bleeding in the eye

Causes of Retinoblastoma

Retinoblastoma occurs when there is a mutation in a gene of DNA in cells of the eye. A gene’s role is to control cell division, and a mutation to a gene prevents this from occurring. The cells divide at an uncontrollable level, accumulate, and form a tumor. 

Specifically, retinoblastoma occurs due to the inactivation of the tumor suppressor retinoblastoma protein (pRb). Most commonly, this involves the biallelic (pertaining to both alleles within a single gene) inactivation of the RB1 gene locus. 

In approximately 40 percent of cases, retinoblastoma is caused by a faulty gene, which is either inherited from a parent or a mutation that occurs early in the child’s development in the womb.

Researchers have found that the human papillomavirus (HPV) genomic DNA has been implicated in cases of retinoblastomas. 

There are few known risk factors for retinoblastomas. However, doctors recommend that general cancer-preventative measures be taken to avoid impacting genes and the genes of your offspring. 

Diagnosis

A diagnosis of retinoblastoma is made by an eye doctor who will likely perform an electroretinogram. This test measures the level of electrical activity in the retina. 

A doctor may also perform an ultrasound, which probes for sound waves to detect echoes that reflect from tissues in the eye. These echoes are then converted by a computer into an image, demonstrating a pattern and allowing for the detection of an abnormality. 

Retinoblastoma can occur in one or both eyes, and the condition is usually diagnosed before a child reaches 1 year of age. A retinoblastoma affecting just one age is more difficult to detect, and it is more commonly diagnosed between the ages of 2 and 3. 

The most noticeable sign of a retinoblastoma is a white reflection in the pupil of the eye, and this is particularly noticeable in photographs. If you notice this in your child, it is critical to see a doctor as soon as possible. Early diagnosis and treatment are crucial.

Treatment of Retinoblastoma

Treatment for a retinoblastoma is similar to that of other forms of cancer. The following are three of the most common forms of treatment specific to this type of cancer:

Chemotherapy

Chemotherapy involves the use of chemicals to kill fast-growing cancerous cells in the body. Drugs that are commonly used in chemotherapy for retinoblastoma consist of etoposide, carboplatin, and vincristine. A combination of two or more drugs may be needed, depending on the progression of the cancer. 

Chemotherapy is associated with side effects, such as these:

• Hair loss
• Fatigue
• Compromised immunity
• Changes in appetite
• Anemia
• Constipation
• Nausea

Radiation

Radiation involves the use of beams of high levels of energy to destroy cancer cells. This commonly consists of the use of x-ray. 

Radiation is often used in combination with chemotherapy to shrink and kill cancerous cells in the retina. However, there are long-term complications associated with radiation, and it is generally not a primary treatment choice for young children.

Laser Therapy

Laser therapy consists of the use of focused and intense light to destroy or remove tissue abnormalities, such as tumorous cells in the retina. There are two common types:

• Laser photocoagulation: This involves the use of a laser beam that is aimed through the pupil and focused on the blood vessels surrounding the tumor, destroying them with heat. 
• Transpupillary thermal therapy: This consists of the application of infrared light directly into the tumor in order to heat and destroy cancerous cells in the retina. This type of treatment can spare some of the blood vessels in the retina.

Complications

If left untreated, retinoblastoma can lead to the following complications:

• Metastasis of the tumor
• Blindness
• Intracranial extension
• Orbital invasion
• Detachment of the retina
• Necrosis of the retina
• Optic nerve invasion
• Secondary neoplasms
• Recurrence of the tumor
• Cataract
• Radiation retinopathy
• Radiation neuropathy
• Temporal bone hypoplasia

Prevention of Retinoblastoma

There are no known risk factors for retinoblastoma that can be prevented. Doctors recommend general cancer-preventative strategies, including these:

• Avoid smoking and the use of tobacco products.
• Moderate alcohol intake.
• Consume a nourishing and balanced diet.
• Maintain a healthy weight
• Avoid excessive exposure to sun and radiation.
• Avoid exposure to hazardous chemicals.

When to See a Doctor

See your doctor if you notice an unusual white coloration in the pupil of your child’s eye. Also see a doctor if you notice one or more of the symptoms listed above. 

It is important to see your doctor if you have a family history of retinoblastoma or another form of cancer in order to perform a full eye examination as early in the child’s life as possible. Early diagnosis is critical for treating cancer, preventing metastasis, and avoiding symptoms like vision loss.

References

1. Can Retinoblastoma be Prevented? (December 2018). American Cancer Society.

2. HPV Infections in Retinoblastoma: A Systematic Review. (October 2021). Journal of Clinical Laboratory Analysis. 

3. Retinoblastoma. (2012). National Organization for Rare Diseases.

4. What Is Retinoblastoma? (December 2013). American Cancer Society.

5. Modern Treatment of Retinoblastoma: A 2020 Review. (October 2020). Indian Journal of Ophthalmology.

6. Publication Trends of Research on Retinoblastoma During 2001–2021: A 20-Year Bibliometric Analysis. (May 2021). Frontiers in Medicine.

7. Retinoblastoma: From Discovery to Clinical Management. (May 2021). The FEBS Journal.